From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936119AbXGMTgT (ORCPT ); Fri, 13 Jul 2007 15:36:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760675AbXGMTgK (ORCPT ); Fri, 13 Jul 2007 15:36:10 -0400 Received: from rtr.ca ([64.26.128.89]:2675 "EHLO mail.rtr.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759357AbXGMTgI (ORCPT ); Fri, 13 Jul 2007 15:36:08 -0400 Message-ID: <4697D425.7000300@rtr.ca> Date: Fri, 13 Jul 2007 15:36:05 -0400 From: Mark Lord User-Agent: Thunderbird 2.0.0.4 (X11/20070604) MIME-Version: 1.0 To: Sergei Shtylyov Cc: Alan Cox , Bartlomiej Zolnierkiewicz , Suleiman Souhlal , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] Make the IDE DMA timeout modifiable References: <20070221011922.GA1777@freefall.freebsd.org> <200702210342.20775.bzolnier@gmail.com> <466EEFD6.9030001@ru.mvista.com> <200706160123.55636.bzolnier@gmail.com> <4693D9B6.4090408@ru.mvista.com> <20070713161612.2f2ebb0b@the-village.bc.nu> <46979652.6040201@rtr.ca> <4697987E.3040406@ru.mvista.com> In-Reply-To: <4697987E.3040406@ru.mvista.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Sergei Shtylyov wrote: > Mark Lord wrote: > >>> O> >> BTW, why the timeout is so damn long? 2*WAIT_CMD is 20 secs, >>> and if DMA is not complete or interrupt pending, it may wait 10 more secs... .. >> I've lost the original question from this thread, but the idea of the > > The original question concerned specifically the DMA command timeout > which is twice more than the usual one, WAIT_CMD (10 seconds). > >> longish >> timeouts was that drive *may* be spun down ("standby"), and thus have >> to spin >> up again to complete media commands. Back then, drives were much >> slower at >> spinning up than nowadays, and the ATA spec says to allow up to 30 >> seconds. > > Well, that doesn't explain the DMA case. When a drive is in standby, we don't send it anything special to wake up. So even DMA commands have to have a long enough timeout to allow for spinning up. Cheers